P2.1 Flashcards
What can forces cause
Changes to the shape or motion of an object
What are two things that objects can do
Move in a straight line at a constant speed
Change their speed and or direction (decelerate or accelerate)
What can graphs help us with
To describe the movement of an object
What are the two graphs
Distance time graphs
Velocity time graphs
What happens when two forces interact
The forces they exert on each other are opposite and equal
What is the resultant force
The overall force acting on an object
What can the resultant force do
May cause a change in its state of rest or movement
What happens if the resultant force is zero on a stationary object
The object will remain stationary
What happens if the resultant force of an object is not zero on the stationary object
The object will accelerate in the direction of the force
What happens if the resultant force of an object is zero on a moving object
The object will continue to move at the same speed and in the same direction
What happens if the resultant force of an object is not zero on a moving object
The object will accelerate in the direction of the resultant force
What does the acceleration of an object determined by
The resultant force acting on it
The mass of the object
What represents the speed on a distance time graph
The gradient
What is velocity
Speed in a given direction
What does the gradient represent on a velocity time graph
Acceleration
What happens when a vehicle travels at a steady speed
The resistive force balances the driving force
What are most resistive forces caused by
Air
The greater the speed of a vehicle
The greater the braking force needed to stop it in a certain distance
What should u understand for a given braking force
The greater the speed, the greater the stopping distance
What is the stopping distance
Thinking distance + braking distance
What is the thinking distance
The distance the vehicle travels during the drivers reaction time
What is the braking distance
The distance the vehicle travels under the braking force
What can the drivers braking distance be affected by
Tiredness
Alcohol
Drugs
Distractions
What happens when the brakes are applied
Work is done by friction force between brake and wheel
Reduces kinetic energy
Increases temperature of brake
What can the vehicles braking distance be affected by
Adverse road and weather conditions
poor conditions of a vehicle
What are included in adverse weather conditions
Wet or icy conditions
What are poor conditions limited to
Brakes and tyres
The faster the object moves through a fluid….
The greater the frictional force that acts on it
Why will an object falling through a fluid initially accelerate
Because of gravity
What might a force acting on an object cause
A change in shape of the object
What will a force applied to an elastic object result in
The object stretching and storing elastic potential energy
How does an elastic object return to its original shape after stretched
The elastic potential energy is turned into kinetic energy so when the force is removed, the object returns to its original shape
What is the relationship between the extension of an elastic object and the force applied
The Extension of an elastic object is directly proportional to the force applied, provided that the limit of proportionality is not exceeded
What is acceleration
How quickly the velocity is changing
What is gravitational force
The force of attraction between all masses
What are the two effects of gravity
On the surface area of earth it makes all things accelerate towards the ground
Gives everything a weight
What is mass
Amount of stuff in an object
Not a force
What is weight
The force of gravity pulling it towards the centre of the earth
What is weight caused by
The pull of the gravitational force
What does friction always do
Slow things down
What is at the opposite direction of movement
Friction
What needs to happen to travel at a steady speed
The driving force needs to balance the frictional force
When do you get friction
When two surfaces come into contact or when an object passes through a fluid
When does drag increase
When speed increase
What needs to happen when you stop a car
The kinetic energy has to be converted to heat energy as friction between the wheels and the brake pads, causing temperature to rise.
What is kinetic energy
Energy of movement
What is power
The rate of doing work
What is one watt
1 joule of energy transferred per second
What is the unit of power
Watt
